Advertisement

Advertisement

Clove extract neutralises asbestos fibres

By Andy Coghlan

Cloves are legendary for their power to numb toothache and, unlikely as it seems, the aromatic spice looks destined for a role in removing asbestos, the fibrous mineral once used routinely to fireproof buildings.

Alternatives to conventional techniques are desperately needed. Usually buildings have to be sealed off during mechanical removal, with air pressure differentials imposed to stop the deadly fibres escaping into the air.

Workers must wear protective clothing to avoid breathing in the lethal fibres, which cause lung cancer and mesothelioma – a cancer of the lung cavity. Even with these precautions, fibres can linger in the air for more than four years, according to research by the US Environmental Protection Agency.

Now Italian chemists have neutralised the lethal fibres using an extract of cloves. When the liquid extract touches the surface of asbestos, it instantly hardens into a polymer similar to lignin, which gives wood its strength. All the potentially hazardous fibres are harmlessly embedded in the polymer and can’t float off into the air.

Advertisement

Free radicals

Bice Fubini and her colleagues in the department of inorganic chemistry at the University of Turin used a combination of hydrogen peroxide and eugenol, a phenol-like chemical found in cloves – Eugenia caryophyllata. Working with colleagues Ivana Fenoglio and Maura Tomatis, Fubini proved that the treatment works on blue asbestos or crocidolite, one of the most dangerous forms of the mineral.

“We knew already that eugenol would polymerise on various silicates, so we thought we’d try it on asbestos, which is a similar silicate,” says Fubini. They’re confident it will also work on the white (chrysotile) and brown (amosite) forms.

As an added bonus, the polymer also mopped up the “free radical” chemical complexes that can lurk on fibres and damage DNA, potentially turning cells cancerous.

Buried danger

The polymer has stayed stable since the experiment, the team report. “It could probably be buried without much danger to people,” she says. “It could also possibly stay where it is in a building, but this would need to be tested absolutely to make sure it would be safe.”

The team hopes that a company will step in to commercialise the idea and work out how best to apply it. “It must be adapted to practical purposes,” she says, with eugenol either extracted from cloves or synthesised.

From June 2002, all owners of business premises in Britain will have to make safe any asbestos in their buildings. “If some-thing seals the asbestos, it’s a far more permanent solution,” says Terry Jago, chief executive of Britain’s Asbestos Removal Contractors Association.